Stockbyte/Thinkstock(TOKYO) -- The ongoing search for an anonymous hacker who has threatened Japanese schools and cities online took an unexpected twist on Wednesday after police found a digital memory card containing email riddles from the person attached to a cat’s collar.

Investigators first learned of the feline’s whereabouts after the hacker sent emails to Japanese media outlets also claiming details of a computer virus. They found the cat wearing a pink collar on the island of Enoshima, just outside Tokyo.

The discovery might give police the big break they have been looking for in a case that has haunted them for months. The National Police Agency said surveillance cameras on the tiny island captured men taking photos of the collared cat and other cats on the island, leading them to believe one of them might be the person responsible, according to the Yomiuri Shimbun newspaper.

The self-described hacker first surfaced six months ago, breaking into the Yokohama city website to post a threatening message detailing a plot to kill students at a local elementary school. A month later, he posted a note on the Osaka city website threatening mass murder, and sent an email to Japan Airlines claiming a bomb had been planted aboard one of its aircraft, according to the Asahi newspaper.

In all, more than a dozen threats have been sent, including one to the prime minister’s office and the school of Emperor Akihito’s grandchild.

Investigators say the elusive perpetrator has left anonymous posts on the popular message board site 2-channel, with a link containing a virus. He has taunted them by hacking into various computers, making it difficult to trace the messages.

Police were embarrassed last year when they arrested four people in connection with the threats, claiming they had “extracted confessions,” only to have the same messages and emails continually posted. They were eventually forced to admit they made a mistake.

On New Year’s Day, the attacker sent email riddles to Japanese newspapers and TV stations, claiming they had been invited to play a game that would lead to “a big scoop.”

National Police has offered a reward of up to $34,000 for information leading to the hacker’s arrest.